The present invention is directed to the field of high purity chemical storage and dispensing for the electronics fabrication industry.
In the fabrication of electronic components, it is frequently required to have various high purity chemicals in liquid or two phase liquid/vapor state contained in canisters of various sizes for supply to the fabrication processes or for cleaning.
It has become the industry norm to contain these canisters of high purity chemical in cabinets typically made of metal and having various automated features such as dispense, level signals and changeout signals for when a canister is empty or near empty.
Since many of the high purity chemicals are toxic, caustic or environmentally controlled, it is important to contain the chemicals in the cabinet to avoid inadvertent vapor discharge or liquid discharge. Historically, inadvertent vapor discharge has been addressed by having the cabinet vented to a house or factory-wide abatement system. However, a risk also prevails for liquid discharge from a failing canister or the connections between the canister and the downstream manifold in the cabinet.
Various trays or dollys with marginal lips or sidewalls are known in the industry to contain modest liquid leaks, such as the advertisement of Victor Associates, Inc. showing a side view of a wheeled polypropylene container with a reservoir for containing 20 gallons of liquid. Secondary containment around the reservoir is mentioned.
Various carts with spill containment are illustrated in the advertisement from Terra Universal, Inc. showing Chem Carts A. through F.
The advertisement of Schumacher for the TransFill II-LRM indicates that 110% spill containment is achieved. This spill containment is achieved by use of a fixed cabinet integral spill pan.
An advertisement by Schumacher for the TransFill II-TFL uses a caster mounted tray with short sidewalls to provide partial secondary containment.
U.S. Pat. No. 5,950,693 shows a cabinet with a transportation cart, FIG. 3, #300, holding a container of chemical. The cart is used to hold a majority of any spill, col. 6, line 50.
The industry has long sought a safe and effective way to store canisters of high purity chemical for dispensing in electronic industry fabrication, as well as other industries. Various partial secondary containments have been used to contain partial spills. Various carts and trays are known for such use. More significant containment has been taught, but it usually requires an inability to access or service the failing container or requires greater height than the typical industry standard cabinet requires. With expensive electronic fabrication floor space at a premium, the industry has long sought an economical space conserving way to contain potentially significant chemical spills from containers while still being able to access the failing container without further spilling leaked liquid chemical and without changing the "footprint" of the cabinet storing the container in the fab.
The present invention addresses the above recited shortcomings of the prior art and succeeds in providing complete secondary containment without increased cabinet height and without elaborate additional carts or trays, as will be set forth in greater detail below.